#include <vector>
#include <string>
#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

int main(int argc, char const *argv[])
{
    ifstream ifs("IODemo.in");
    ofstream ofs("IODemo.out");
    int x = 0, y = 0;
    while(!ifs.eof()){
        ifs>>x>>y;
        cout<<"x="<<x<<" y="<<y<<endl;
        ofs<<"x="<<x<<" y="<<y<<endl;
    }
    string hw{"Hellow, World"};
    cout<<hw[0]<<endl;
    
    
    string test{"ABCDAB"};
    for(int pos = 0; pos+2 <= test.size(); ++pos){
        cout<<test.substr(pos, 2)<<endl;
    }
    return 0;
}
